Family ties: Children with an autistic parent or siblings have nine times the usual odds of having autism.
Ken Wiedemann / Getty Images
Children in families with a history of brain conditions are at increased odds of being autistic, a large study in Sweden suggests1. The more closely related the family members with these conditions, the greater the child’s chances of having autism.
Other studies have reported similar trends: A child’s odds of having autism increase if she has a sibling with autism, attention deficit hyperactivity disorder (ADHD) or intellectual disability, or a parent with schizophrenia, depression, bipolar disorder or anxiety2,3,4.
The new study looked at family history of these conditions, as well as epilepsy and more than a dozen others, and included grandparents, aunts, uncles and cousins.
In autism studies, scientists tend to focus on older siblings, “but many people with autism don’t have an older sibling with autism,” says lead investigator Brian Lee, associate professor of epidemiology and biostatistics at Drexel University in Philadelphia. “Family history, in nearly every aspect of medicine, is an incredibly strong determinant of outcome.”
Lee and his colleagues examined records from 10,920 children with autism and 556,516 typical children enrolled in the Stockholm Youth Cohort, an ongoing study of children born in that city. The researchers used national registries to identify the children’s more than 8 million relatives and those relatives’ diagnoses.
Children who have a first-degree relative — a sibling or parent — with a brain condition other than autism have up to 4.7 times the usual odds of having autism, the study found. And they have up to 7.6 times the odds of having both autism and intellectual disability.
The results jibe with evidence linking risk factors for autism with those for other conditions, says James Crowley, associate professor of genetics and psychiatry at the University of North Carolina at Chapel Hill, who was not involved in the study. “Genes that predispose to one psychiatric or neurologic disorder often predispose to another,” he says.
Relative risk:
The risk of autism — with or without intellectual disability — decreases as the genetic distance between the child and the affected family member increases.
“This is really telling us that there seems to be a general liability factor, which is genetically transmitted, to having a variety of different psychiatric and neurological disorders,” says Alan Brown, professor of psychiatry and epidemiology at Columbia University, who was not involved in the study. The findings appeared in March in JAMA Network Open.
The study also found that the 8,354 children who have autism alone are more likely to have a relative with one of these conditions than are the 2,566 children who have both autism and intellectual disability.
Children with an autistic parent or sibling have 9 times the usual odds of autism and 4.1 times the odds of having autism with intellectual disability. But children who have a parent or sibling with both autism and intellectual disability have 14.2 times the usual odds of also having both conditions and 3.8 times the odds of having autism alone.
These findings support the idea that the genetics of autism with intellectual disability differs from that of autism alone, says Jakob Grove, associate professor of biomedicine at Aarhus University in Denmark, who was not involved in the study.
Lee and his colleagues are analyzing records in national registries in Denmark to look at autism’s relationship to family history of brain and other health conditions.
FAQs
Research tells us that autism tends to run in families, and a meta-analysis of 7 twin studies claim that 60 to 90% of the risk for autism comes from your genome. If you have a child with autism, you are more likely to have another autistic child. Your other family members are also more likely to have a child with ASD.
What causes autism to run in families? ›
Although the cause of ASD is known in some people and not known in others, genetics, biology, and environment are all important factors. Having older parents, a difficult birth, or infections during pregnancy are all examples of factors that might increase the risk for having ASD.
What are the most common genetic causes of autism? ›
[85] reported genetic findings from more than 900 patients presenting with ASD using standard karyotype chromosome analysis, fragile X DNA testing (Fragile X Syndrome is recognized as the most common cause of familial intellectual disability and/or autism, primarily affecting males) and chromosomal microarrays.
What are the family issues related to ASD? ›
Having a child with Autism the impact on various aspects of family lives are affected including housekeeping, finances, emotional and mental health of parents, marital relationships, physical health of family members, limiting the response to the needs of other children within the family, poor sibling relationships, ...
What are the 3 main causes of autism? ›
There are many different factors that have been identified that may make a child more likely to have ASD, including environmental, biologic, and genetic factors.
What is the strongest cause of autism? ›
Genetic factors play a significant role in the development of ASD. Research suggests that genetic factors contribute to about 80-90% of the risk for developing ASD, while environmental factors contribute to about 10-20% of the risk. ASD tends to run in families, indicating the importance of genetic factors.
What is the biggest risk factor for autism? ›
Although scientists are still trying to understand why some people develop autism and others don't, risk factors may include:
- A sibling with autism.
- Older parents.
- Certain genetic conditions, such as Down, fragile X, and Rett syndromes.
- Very low birth weight.
As society learns more about autism, we also learn about a parent's role in its development. Environmental factors are known to play a role. Still, research suggests genetic mutations are the most common factors in developing autism, and recent research suggests autism is inherited from the father.
Who is more likely to carry the autism gene? ›
While both parents may contribute to a child's risk of developing autism, research has also shown that the mother's genetics may play a slightly larger role. This is because the majority of genetic mutations associated with autism are thought to occur spontaneously in the egg or sperm cells of the mother.
Are you born with autism or can you develop it? ›
It's something you're born with. Signs of autism might be noticed when you're very young, or not until you're older. If you're autistic, you're autistic your whole life. Autism is not a medical condition with treatments or a "cure".
They then compared these groups with people of the same age and sex, who had not been diagnosed as autistic. The researchers found that autistic men without a learning disability had an average estimated life expectancy of 74.6 years, and autistic women without a learning disability, around 76.8 years.
Can a whole family be autistic? ›
Autism spectrum disorder is an umbrella diagnosis. Lots of different kinds of developmental conditions can cause a child to develop autism, from single-gene disorders to a complex interplay of genetic and environmental factors. Research shows that autism can indeed run in families.
What are five conditions that are commonly comorbid with ASD? ›
A range of physical and mental-health conditions frequently accompany autism. They include, but are not limited to, the following:
- Gastrointestinal (GI) problems.
- Epilepsy.
- Feeding issues.
- Disrupted sleep.
- Attention-deficit/hyperactivity disorder (ADHD)
- Anxiety.
- Depression.
- Obsessive compulsive disorder (OCD)
The CDC says more children are being diagnosed with autism than ever before. The rates may reflect growing awareness of autism spectrum disorder and a focus on getting more children into treatment. Other factors including air pollution, low birth weight, and stress may also be behind the increase in diagnoses.
How can I prevent having a child with autism? ›
Can You Prevent Autism?
- Live healthy. Have regular check-ups, eat well-balanced meals, and exercise. ...
- Don't take drugs during pregnancy. Ask your doctor before you take any medication. ...
- Avoid alcohol. ...
- Seek treatment for existing health conditions. ...
- Get vaccinated.
Fact or Fiction: Are There Different Types of Autism
- Autism diagnoses pre-2013.
- Autistic disorder.
- Childhood disintegrative disorder.
- Pervasive developmental disorder (PDD-NOS)
- Asperger syndrome.
- Today's Autism Spectrum Disorder.
- Level 2: Low-Functioning Autism (LFA)
- Level 3: Classic Autism (CA)
Although the exact cause of autism is still unknown, there is evidence to suggest that genetics play a significant role. Since autism is less prevalent in females, autism was always thought to be passed down from the mother. However, research suggests that autism genes are usually inherited from the father.
How is autism genetically inherited? ›
Autism is highly heritable: It is estimated at least 50% of genetic risk is predicted by common genetic variation and another 15-20% is due to spontaneous mutations or predictable inheritance patterns. The remaining genetic risk is yet to be determined.
